Method for removing silicon and phosphorus from solution

Abstract

The invention provides a method for removing silicon and phosphorus from a solution, which comprises the following steps: firstly, filtering the solution to be treated containing silicon and phosphorus, then adjusting the pH value, so that silicon and phosphorus exist in the form of ions easy to adsorb, and activating the optimal adsorption activity of a composite adsorbent; afterwards, the solution to be treated is subjected to adsorption treatment through the composite adsorbent, activated aluminum oxide in the composite adsorbent is responsible for providing a basic adsorption framework and chemical adsorption force, the modified bentonite makes up for the defects of the activated aluminum oxide in dispersity and part of adsorption sites, and nano titanium dioxide strengthens the adsorption effect by means of high activity and selectivity; therefore, the removal efficiency of silicon and phosphorus is greatly improved; then, the composite adsorbent particles adsorbing silicon and phosphorus and impurities are coagulated into large and dense flocs through the mixed flocculant, solid-liquid separation is accelerated, and secondary suspension is avoided; and finally, adsorbing residual silicon and phosphorus ions through deep filtration so as to realize efficient removal of silicon and phosphorus impurities in the solution.

Description

Technical Field

[0001] The invention relates to the technical field of industrial wastewater treatment, in particular to a method for removing silicon and phosphorus from a solution. Background Art

[0002] In many industrial production processes and water resource treatment scenarios, solutions often contain impurities such as silicon and phosphorus. For example, in chemical production, silicon and phosphorus impurities can affect product purity and quality, leading to equipment scaling and reduced production efficiency. In wastewater treatment, the discharge of phosphorus-containing wastewater can cause eutrophication, leading to algae blooms and disrupting the aquatic ecological balance. In drinking water treatment, excessive silicon and phosphorus can also pose potential risks to human health.

[0003] Currently, methods for removing silicon and phosphorus from solutions mainly include chemical precipitation, ion exchange, and adsorption. Chemical precipitation typically requires the addition of large amounts of chemicals, which can easily lead to secondary pollution, and the precipitation effect is significantly affected by factors such as the solution's pH and temperature. Ion exchange is highly selective for specific ions, but the resin easily saturates, requiring frequent regeneration and resulting in high operating costs. While adsorption is relatively simple to operate, the adsorbent has limited adsorption capacity, resulting in unstable adsorption effects and difficulty achieving deep removal of silicon and phosphorus.

[0004] Therefore, there is an urgent need to develop a new method for removing silicon and phosphorus from solutions that is efficient, environmentally friendly and economical. Summary of the Invention

[0005] The object of the present invention is to provide a method for removing silicon and phosphorus from a solution, so as to improve the technical problems of the existing method for removing silicon and phosphorus from a solution, such as limited adsorption capacity, high cost, and easy generation of secondary pollution, so as to achieve efficient removal of silicon and phosphorus impurities in the solution, reduce treatment costs, reduce secondary pollution, and improve the purification quality of the solution.

[0006] To solve the above technical problems, the present invention provides a method for removing silicon and phosphorus from a solution, comprising: S10, filtering the solution to be treated containing silicon and phosphorus and then adjusting the pH value; S20, adding a composite adsorbent to the solution to be treated and performing adsorption treatment, stirring to obtain a first mixed solution, wherein the composite adsorbent includes activated alumina, modified bentonite and nano-titanium dioxide; S30, adding a mixed flocculant to the first mixed solution and performing flocculation and precipitation treatment, and obtaining a second mixed solution and silicon-phosphorus flocculent precipitate after solid-liquid separation; S40, performing deep filtration on the second mixed solution to obtain a purified solution.

[0007] Preferably, in step S10, the pH value of the solution to be treated after the pH adjustment treatment is 6-8. Preferably, in the composite adsorbent of step S20, the mass ratio of activated alumina, modified bentonite and nano-titanium dioxide is (2.5-3.5): (1.5-3):1.

[0008] Preferably, in step S20: the adsorption temperature is 25-35° C., the stirring speed is 150-200 r / min, and the stirring time is 60-90 min.

[0009] Preferably, in step S30: the mixed flocculant includes polyaluminum chloride and polyacrylamide.

[0010] Preferably, in step S30, the amount of polyaluminum chloride added to each liter of the first mixed solution is 50-80 mg, and the amount of polyacrylamide added to each liter of the first mixed solution is 1-3 mg.

[0011] Preferably, in step S40: the second mixed solution is subjected to deep filtration treatment by a filtration device equipped with activated carbon fibers.

[0012] Preferably, in step S10, the silicon content of the solution to be treated is 18-20 mg / L, and the phosphorus content of the solution to be treated is 12-15 mg / L.

[0013] Preferably, in step S40: the silicon content of the purified solution is less than or equal to 1.2 mg / L, and the phosphorus content of the solution to be treated is less than or equal to 0.4 mg / L.

[0014] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides a method for removing silicon and phosphorus from a solution. The method first filters the solution containing silicon and phosphorus to be treated and then adjusts the pH value to allow silicon and phosphorus to exist in the form of easily adsorbed ions and activate the optimal adsorption activity of the composite adsorbent. Then, the composite adsorbent is used to adsorb the solution to be treated. The activated alumina in the composite adsorbent is responsible for providing the basic adsorption framework and chemical adsorption capacity. The modified bentonite compensates for the deficiencies of the activated alumina in dispersibility and partial adsorption sites. Nano-titanium dioxide enhances the adsorption effect with high activity and selectivity, and together they construct a multi-level, comprehensive adsorption system, thereby significantly improving the removal efficiency of silicon and phosphorus. Then, a mixed flocculant agglomerates the composite adsorbent particles adsorbed with silicon and phosphorus and impurities into large and dense flocs, accelerating solid-liquid separation and avoiding secondary suspension. Finally, the residual silicon and phosphorus ions are adsorbed by deep filtration to achieve efficient removal of silicon and phosphorus impurities in the solution. The present invention can effectively reduce the treatment cost of silicon and phosphorus removal, reduce secondary pollution, and improve the purification quality of the solution to be treated. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a flow chart of a method for removing silicon and phosphorus from a solution provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] The purpose of the present invention is to overcome the above-mentioned technical deficiencies and provide a method for removing silicon and phosphorus from a solution. The process includes a "pretreatment stage - adsorption reaction stage - flocculation and precipitation stage - deep treatment stage", aiming to achieve efficient removal of silicon and phosphorus impurities in the solution, reduce treatment costs, reduce secondary pollution, and improve the purification quality of the solution.

[0018] See also Figure 1 , Figure 1 A flow chart of a method for removing silicon and phosphorus from a solution provided in an embodiment of the present invention; wherein the method for removing silicon and phosphorus from a solution specifically includes: S10, filtering the solution to be treated containing silicon and phosphorus and then adjusting the pH value.

[0019] Specifically, step S10 further includes: Pretreatment: The silicon-phosphorus-containing solution to be treated is filtered to remove larger suspended solids and impurities. The pH of the solution is then adjusted to between 6 and 8 to create suitable conditions for subsequent treatment. Filtration effectively intercepts larger suspended solids and impurities in the solution to be treated, preventing them from clogging the adsorbent pores and interfering with the reaction process. Adjusting the solution pH to between 6 and 8 allows silicon and phosphorus to exist in an ionic form conducive to adsorption, activates the active sites of the composite adsorbent, and creates an optimal hydrolysis environment for the flocculant, significantly improving the efficiency of subsequent adsorption, flocculation, and sedimentation processes, ensuring efficient and stable operation of the silicon-phosphorus removal process.

[0020] In one embodiment, the silicon content of the solution to be treated is 18-20 mg / L, and the phosphorus content of the solution to be treated is 12-15 mg / L.

[0021] S20, adding a composite adsorbent to the solution to be treated and performing adsorption treatment, and obtaining a first mixed solution after stirring, wherein the composite adsorbent includes activated alumina, modified bentonite and nano-titanium dioxide.

[0022] Specifically, step S20 further includes: Adsorption reaction stage: A composite adsorbent, composed of activated alumina, modified bentonite, and nano-titanium dioxide in a mass ratio of (2.5-3.5):(1.5-3):1, is added to the solution to be treated. The mixture is stirred at a speed of 150-200 rpm for 60-90 minutes at a temperature of 25-35°C to allow the composite adsorbent to fully contact and adsorb the silicon and phosphorus in the solution.

[0023] Specifically, the composite adsorbent, composed of activated alumina, modified bentonite, and nano-titanium dioxide in the aforementioned mass ratio, fully leverages the advantages of each component: activated alumina provides abundant adsorption sites and chemical adsorption capacity, modified bentonite enhances dispersibility and interlayer adsorption, and nano-titanium dioxide, with its high activity, strengthens adsorption selectivity. The three synergistically form a highly efficient adsorption system. Simultaneously, the temperature is controlled between 25 and 35°C, a range that is conducive to maintaining adsorbent activity and ion diffusion rate. Stirring at a speed of 150 to 200 r / min for 60 to 90 minutes ensures uniform dispersion of the adsorbent and increases the probability of collision with silicon and phosphorus ions, while avoiding excessive stirring that disrupts the floc structure. This ensures that the adsorbent fully contacts and reacts with the silicon and phosphorus in the solution, significantly improving silicon and phosphorus removal efficiency and adsorption capacity.

[0024] In one embodiment, the mass ratio of activated alumina, modified bentonite and nano-titanium dioxide in the composite adsorbent is 3:2:1.

[0025] S30, adding a mixed flocculant to the first mixed solution and performing flocculation and precipitation treatment, and obtaining a second mixed solution and silicon-phosphorus flocculent precipitate after solid-liquid separation.

[0026] Specifically, step S30 further includes: Flocculation and precipitation stage: After the stirring reaction is completed, a mixed flocculant of polyaluminum chloride and polyacrylamide is added to the first mixed solution. The dosage of polyaluminum chloride is 50-80 mg per liter of the first mixed solution, and the dosage of polyacrylamide is 1-3 mg per liter of the first mixed solution. Stirring is continued for 10-15 minutes to allow the composite adsorbent particles adsorbed with silicon and phosphorus to aggregate and form larger flocs. The mixture is then allowed to settle for 30-60 minutes to achieve solid-liquid separation.

[0027] Specifically, during the flocculation and sedimentation stage, polyaluminum chloride and polyacrylamide are added in a specific ratio, combined with precise stirring and settling time, to achieve efficient solid-liquid separation. A dosage of 50-80 mg of polyaluminum chloride per liter of solution fully hydrolyzes to produce a polynuclear hydroxyl complex, compressing the double electrical layer on the particle surface and exerting adsorption charge neutralization, thereby destabilizing the composite adsorbent particles adsorbed with silicon and phosphorus. Polyacrylamide is added at a dosage of 1-3 mg per liter, and its long-chain molecules can quickly bridge between particles. Stirring is continued for 10-15 minutes to promote thorough mixing and reaction between the flocculant and particles, forming large, dense flocs. Settling is then allowed to settle for 30-60 minutes to ensure that the flocs fully settle by gravity, effectively achieving solid-liquid separation. This reduces the burden on subsequent deep processing and ensures effective silicon and phosphorus removal.

[0028] S40, performing deep filtration on the second mixed solution to obtain a purified solution.

[0029] Specifically, step S40 further includes: Advanced treatment stage: The second mixed solution (supernatant) after precipitation is passed through a filtration device equipped with activated carbon fiber to further remove trace silicon, phosphorus impurities and other organic pollutants remaining in the second mixed solution to obtain a purified solution.

[0030] Specifically, the deep treatment stage utilizes the powerful adsorption properties of activated carbon fibers to finely purify the second mixed solution after precipitation. Activated carbon fibers have a large specific surface area and a well-developed pore structure. Through the dual effects of physical and chemical adsorption, they can efficiently capture trace silicon and phosphorus impurities remaining in the solution, while also adsorbing and retaining other organic pollutants. After treatment through this filtration device, the solution is further purified, ensuring that the final purified solution meets stringent water quality standards, achieving deep removal of silicon, phosphorus, and organic pollutants, and ensuring the effectiveness of the entire silicon and phosphorus removal process.

[0031] In one embodiment, when the silicon content of the solution to be treated is 18-20 mg / L and the phosphorus content is 12-15 mg / L, the silicon content of the purified solution is less than or equal to 1.2 mg / L, and the phosphorus content is less than or equal to 0.4 mg / L.

[0032] The technical solution of the present application is now described in further detail with reference to specific embodiments.

[0033] Example 1: Example 1 of the present invention provides a method for removing silicon and phosphorus from a solution, and the specific steps are as follows: Step 1, pretreatment: Take 100L of industrial wastewater containing silicon and phosphorus, first filter it through a 0.45μm filter membrane to remove large particle impurities, and then use sodium hydroxide solution to adjust the pH value of the wastewater to 7.

[0034] Step 2, adsorption reaction: add 1 kg of composite adsorbent to the pretreated wastewater, and stir the mixture at a temperature of 30° C. and a stirring speed of 180 r / min for 75 minutes.

[0035] Step 3: Flocculation and sedimentation: After stirring, add 65 mg / L of polyaluminum chloride and 2 mg / L of polyacrylamide, continue stirring for 12 minutes, then let it settle for 45 minutes and discharge the precipitated sludge at the bottom.

[0036] Step 4, Advanced Treatment: The supernatant is filtered through a filter tank filled with activated carbon fiber to obtain a purified solution. Testing showed that the silicon content in the treated solution was reduced from an initial 20 mg / L to 1.5 mg / L, a removal rate of 92.5%. The phosphorus content was reduced from an initial 15 mg / L to 0.5 mg / L, a removal rate of 96.7%.

[0037] Example 2: Example 2 of the present invention provides a method for removing silicon and phosphorus from a solution, and the specific steps are as follows: Step 1, pretreatment: Take 200L of domestic sewage containing silicon and phosphorus, filter it through a sand filter, and adjust the pH value of the sewage to 6.5 with hydrochloric acid.

[0038] Step 2, adsorption reaction: add 2 kg of composite adsorbent to the sewage, and stir the reaction at a stirring speed of 150 r / min at 25°C for 90 minutes.

[0039] Step 3, flocculation precipitation: add 50 mg / L polyaluminum chloride and 1 mg / L polyacrylamide in sequence, stir for 10 minutes and then let it settle for 60 minutes.

[0040] Step 4, Advanced Treatment: The supernatant was filtered through an activated carbon fiber filter. Testing showed that the silicon content in the treated solution dropped from an initial 18 mg / L to 1.2 mg / L, a removal rate of 93.3%. The phosphorus content dropped from an initial 12 mg / L to 0.4 mg / L, a removal rate of 96.7%.

[0041] Combining the silicon and phosphorus removal results of Example 1 and Example 2, it can be seen that the composite adsorbent used in the present invention has good adsorption performance for silicon and phosphorus. Through reasonable process steps and parameter control, efficient removal of silicon and phosphorus impurities in the solution can be achieved, and the silicon removal rate can reach more than 90%, and the phosphorus removal rate can reach more than 95%.

[0042] Compared with the prior art, the method for removing silicon and phosphorus from a solution provided by the present invention has the following beneficial effects: 1. Efficient removal: The composite adsorbent used in the present invention has good adsorption performance for silicon and phosphorus. Through reasonable process steps and parameter control, it can achieve efficient removal of silicon and phosphorus impurities in the solution. The silicon removal rate can reach more than 90%, and the phosphorus removal rate can reach more than 95%.

[0043] 2. Environmental protection and economy: This method uses relatively few chemical agents, and the composite adsorbent can be reused through simple regeneration treatment, which reduces treatment costs and secondary pollution.

[0044] 3. Easy to operate: The entire treatment process is simple, the equipment structure is reasonable, and it is easy to realize automatic control, which is suitable for large-scale industrial applications.

[0045] In summary, different from the existing technology, the present invention provides a method for removing silicon and phosphorus from a solution. The method first filters the solution to be treated containing silicon and phosphorus and then adjusts the pH value to make silicon and phosphorus exist in the form of easily adsorbed ions and activate the optimal adsorption activity of the composite adsorbent; then, the composite adsorbent is used to adsorb the solution to be treated. The activated alumina in the composite adsorbent is responsible for providing the basic adsorption framework and chemical adsorption force, the modified bentonite makes up for the deficiencies of the activated alumina in dispersibility and partial adsorption sites, and the nano-titanium dioxide enhances the adsorption effect with high activity and selectivity, together constructing a multi-level, all-round adsorption system, thereby greatly improving the removal efficiency of silicon and phosphorus; then, the mixed flocculant condenses the composite adsorbent particles and impurities adsorbed with silicon and phosphorus into large and dense flocs, accelerates solid-liquid separation, and avoids secondary suspension; finally, the residual silicon and phosphorus ions are adsorbed by deep filtration to achieve efficient removal of silicon and phosphorus impurities in the solution. The present invention can effectively reduce the treatment cost of silicon and phosphorus removal, reduce secondary pollution, and improve the purification quality of the solution to be treated.

[0046] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0047] The above embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for removing silicon and phosphorus from a solution, characterized in that: include: S10, filtering the solution to be treated containing silicon and phosphorus and then adjusting the pH value; S20, adding a composite adsorbent to the solution to be treated and performing adsorption treatment, and obtaining a first mixed solution after stirring, wherein the composite adsorbent includes activated alumina, modified bentonite, and nano-titanium dioxide; S30, adding a mixed flocculant to the first mixed solution and performing flocculation and precipitation treatment, and obtaining a second mixed solution and silicon-phosphorus flocculent precipitate after solid-liquid separation; S40, performing deep filtration on the second mixed solution to obtain a purified solution.

2. The method for removing silicon and phosphorus from a solution according to claim 1, wherein In the step S10, the pH value of the solution to be treated after the pH adjustment treatment is 6-8.

3. The method for removing silicon and phosphorus from a solution according to claim 1, wherein: In the composite adsorbent of step S20, the mass ratio of activated alumina, modified bentonite and nano-titanium dioxide is (2.5-3.5): (1.5-3):

1.

4. The method for removing silicon and phosphorus from a solution according to claim 1, wherein In the step S20, the adsorption temperature is 25-35° C., the stirring speed is 150-200 r / min, and the stirring time is 60-90 min.

5. The method for removing silicon and phosphorus from a solution according to claim 1, wherein: In the step S30: the mixed flocculant includes polyaluminum chloride and polyacrylamide.

6. The method for removing silicon and phosphorus from a solution according to claim 5, wherein: In the step S30, the amount of polyaluminum chloride added to each liter of the first mixed solution is 50-80 mg, and the amount of polyacrylamide added to each liter of the first mixed solution is 1-3 mg.

7. The method for removing silicon and phosphorus from a solution according to claim 1, wherein: In the step S40, the second mixed solution is subjected to the deep filtration treatment by a filtration device equipped with activated carbon fibers.

8. The method for removing silicon and phosphorus from a solution according to claim 1, wherein: In the step S10, the silicon content of the solution to be treated is 18-20 mg / L, and the phosphorus content of the solution to be treated is 12-15 mg / L.

9. The method for removing silicon and phosphorus from a solution according to claim 8, wherein: In the step S40, the silicon content of the purified solution is less than or equal to 1.2 mg / L, and the phosphorus content of the solution to be treated is less than or equal to 0.4 mg / L.

Images